1. Field of the Invention
The present invention relates to a method of fabricating a varistor with zinc phosphate insulation and the varistor fabricated by the method, and more particularly to a fabricating method that provides flat insulation on outer surfaces of the varistor.
2. Description of Related Art
The prior art discloses a method of fabricating the insulation for a varistor. The varistor has two end terminals and a ceramic body with an outer surface. The method uses a chemical reaction between a phosphoric acid and the surface of the ceramic body to form zinc phosphate insulation on the ceramic body. The zinc phosphate insulation isolates the surface of the ceramic body and the electrolyte, but the zinc phosphate insulation reacts chemically with the ceramic body, so that the body is etched and has a rough surface. A metal material used to coat the end terminals is inadvertently electroplated on the insulation.
Therefore, another method of fabricating the insulation to overcome the problems was developed. The fabricating method uses zinc phosphate deposits on the surface of the ceramic body to keep from etching the surface. Therefore the surface of the body is kept flat, but the insulation layer is still rough. However, metal material is still electroplated on the zinc phosphate and the yield is not good. Therefore this fabricating method does not solve all of the problems.
Therefore, an objective of the present invention is to provide an improved method for fabricating zinc phosphate insulation for a varistor to mitigate and/or obviate the aforementioned problems.